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View Full Version : Identify this pool wall please



John Cahill
04-29-2013, 06:47 PM
I rarely see above ground gunite. The following picture is of a pool half in a hill and half out. 10 years old. No movement. Good condition. Does anyone recognize the gunite form that was used? Is this common? I have never seen an exposed form.

Jerry Peck
04-29-2013, 07:42 PM
What you are looking at is not the gunite, that is the form used to back up the gunite which is blown onto/against that form.

That form is a paper-type product with wire mesh stitched to the paper to serve as support for the form.

Typically, that is not left exposed as that would typically be below ground and be hidden when the pool is back-filled around the form/gunite pool walls.

The times that I have seen where that would be exposed it has been covered with stone/rock/brick/more gunite to look like large rocks/boulders.

*IF* (the big "IF") the steel in the pool and the thickness of the wall was engineered to be left exposed, then there is nothing wrong with leaving it exposed, however, if no additional steel was used and/or the pool wall was not made thicker for extra strength, then the pool wall is intended to have earth pressure supporting the water pressure from within the pool, that wall could fail - but ... unless you have access to the original design and plans for the pool I would not want to raise that issue (unless you see signs of failure) as it has lasted 10 years and likely will last much longer.

This is one of those items you mention as having no way to determine the suitability of the pool construction for not having backfill supporting the pool walls, but that you see no signs of failure and that the engineers who design these installation are supposed to take that into consideration for their pool wall design - which you have no way of documenting or verifying, contact the original pool engineer if there are any questions regarding the suitability of this pool design and installation. The typical design difference is to increase the steel from #4 bars placed on 12" centers both ways, to being #4 (or #5) bars placed on 6" centers both ways. That is also how they typically strengthen the pool walls and bottom where the pool walls and bottom are within the angle of repose of the soil supporting the house (with a 45 degree angle), i.e., if the pool is 5 feet deep at the wall, then the plane of the wall of the pool should be at least 5 feet from the plane of the footing, if within that 45 degree angle of repose the steel is typically doubled as described, and the walls are shot thicker with gunite (maybe from 6" thick to 7" or 8" thick) - all depends on the engineer, but that is what I have seen. That unsupported (exposed) wall might have had #4 or #5 bars on 3" centers both ways, and the wall thickness might have been increased to 9" or even to 12" - again, all depends on the engineer.